Causes of Flooding

Lack of vegetation means less interception decreasing the lag time and increasing the discharge

Saturated ground means an increase in surface run off

Flat ground increases chance of flood

The point of a confluence creates an increase in discharge

Human Causes

Urban landscape increases surface run off because of impermeable ground and pipelines carrying water to the river faster decreasing lag time and increasing discharge

Agriculture removes vegetation, decreasing interception and so increasing discharge. The lack of vegetation also means there is an increase in erosion putting more sediment in the river decreasing the cross sectional area and so decreasing the amount of water the river can hold

Dams purposefully flood land

Flood Management

Hard Engineering - Flooding prevention using man made structures (tends to be expensive and cause problems further downstream)Soft engineering - Flooding prevention by decreasing the discharge by adapting the channel environment (requires long term management)

Enlarging channel - increases the amount of discharge the river can hold decreasing the chance of the discharge exceeding the bankfull discharge.Embankments / levees / flood walls / revetments - increases the amount of discharge the river can holdRelief channel - a extra tributary leading away from the original channel redirecting excess water away from the flood prone areaNew river channel - building a new river channel passes the river past urban environments in an enlarged channel.Dams - controls the discharge of the riverFlood abatement - manages the land use in the upper course of the river using reforestationBuilding above flood plain - decreases the damage to properties and allows for ground to be saturated reducing the magnitude of the flood

Embankments on the River Thames, London , UK

The new artificial river channel for The Blackwater River, Basingstoke, UK

Aswan High Dam, Egypt

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Chubby Revision: A Level students revision for Chemistry, Physics, Geography and Maths